Dust-collecting system for coal-handling plants



April 21, 1931. R, w. ARMS =1 ,801,

DUST COLLECTING SYSTEM FOR COAL HANDLING PLANTS Fil ed Aug. 24, 1928 s Sheets-Sheet 1 April 21, 1931. R. w. ARMS 1,801,255

DUST COLLECTING SYSTEM FOR COAL HANDLING PLANTS Filed Aug. 24, 1928 3 Sheets-Sheet 2 fl? V67? fa? April 21, 1931. R. w. ARMS 1,801,255

DUST COLLECTING SYSTEM FOR COAL HANDLING PLANTS Filed Aug. 24, 1928 I5 Sheets-Sheet 3 Patented Apr. 21, 1931 UNITED STATES PATENT OFFICE RAY. W. ARMS, OF CHICAGO, ILLINOIS, ASSIGNOR TO ROBERTS AND SCHAEFEB; GOM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS cleaning tables in the DUST-COLLECTING SYSTEM. FOR COAL-HANDLING- PLANTS Application filed August 24, 1928. Serial No. 301,740.

eration of the plant whether it comes from coal cleaning tables or from other sources so as to provide a substantially dustless' coal handling plant.

Tn general'l propose to provide a series of batteries of air cleaning tables=,-a ll the tables in each battery preferably handling coa-l of' the same general size and having the same general air requirement but thetablesin different batteries handling coal of considerably different sizes and having considerably diilerent air requirements though under some circumstances the limitation as regards size and air requirements of the table'in any particular battery may be dispensed. with, in which case we would-havea seriesof different batteries having different air requirements and handlingdifierent'sizedcoal.

I propose to associate with each battery no'matterwhat its character and no matter what the air requirement" ofthe battery is a plenum chamber which is merely a relatively large size chamber through which air circulatesat' relativelylow velocity. The working 7 air for each table in thebattery will be" sup pliedfrom this plenum chamber, the pressure inthe-plenum chamber'being provided by a single fan, pump or blower.

Preferably theplenumchamber which supplies air to the battery handling the finest coal'willreceive its air'supply fromthe outside atmosphere or from-the dust collector. The plenum chamber for the other batteries will receive dust laden air drawn from hoods enclosing the tables of the preceding battery and such plenum chambers will serve also as settling-chambersbeing preferably equipped with a screw conveyor at the bottom whichwill take out the large particles settled out from the dust laden air.

Each table will be provided with a hood and the air will be drawn from this hood into the next plenum chamber but since it is necessary to have openings between the-hood and the table to permit workmen to inspect the operation and to permit coal to pass to and be discharged from the table, there will al ways be a certain amount of clearance and the suction pipe that leads from the hood to the plenum chamber will draw in the spent dust laden air which is passed up through the deck plus a certain amount of make-up air approximately perhaps twenty percent of the total.

The air requirement of each succeeding battery is generally greater than the air re quirement of the preceding battery and if the make-up air that is drawn in around the hood is sufficient, no further attention is required; If, however, it is not sufficient, I propose to discharge into that plenum chamber dust laden air from some other source as for instance from the classifying screen or from bucket elevators, conveyor lines or any other place about the plant where dust laden air may be found.

battery is less than for a preceding battery, I will discharge air from the succeeding plenum chamber to the dust line leading to the dust collector.

The dust laden air from the hood enclosing the last battery in the series is conducted by the dust line to the dust separator and into this dust line will also discharge dust laden airfroni any of the sources of dust laden air other than the tables above referred to which may be left over after the system has been balanced.

Of course, the passages leading to and from-each deck and the passages leading into the plenum chambers or the dust line from the other sources of' dust laden air will be equipped-with control valves so that the operator may adjust and manipulate the system to produce satisfactory balanced operation.

In general, we will then have a system where air is under pressure only between the If on the other hand, the air requirement for a succeeding blower through the passage leading therefrom to the plenum chamber and through the passages leading from the plenum chambers to the deck. This system can and must be made dust and air tight as otherwise dust will escape to the room. All other parts of the system are under suction and so any leakage merely results in adding to the amount of air which must be handled but does not result in the discharge of dust out of the system; This applies not merely to the table-s but to screens, conveyors and other elements of the system so that all the dust which would otherwise be present in the air in the working part of the house and causes the possibility of a dangerous dust situation or make working condi tions unpleasant will be avoided.

Experience showsthat by this re-use of the airthe total power required to handle dust laden air after its work has been done, and the capacity of the dust collector required to take the dust out of the air is reducedto a minimum.. This latter is especially important'because the size and expense of the dust collector depends not upon the amount of dust present but upon the total volume of air which must be handled.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein Figure 1 is a diagrammatic view showing one form of the exemplification of my solution of the problem;

Figure 2 is a section along the lineZ-EZ of Figure 1;. p v

Figue 3 is a View similar to Figure 1 showing a different solution'of the problem having, however, features of similarity.

' Like parts are indicated by like characters throughout the specification and drawings.

A is a dust collector adapted'to take out substantially one hundred percent of the dust from the air A is a passage leading therefrom to a fan or blower A driven by a motor A This fan or blower A discharges through a passage A? into a plenum chamber A It will be'noted that this plenum chame her is of relatively large cross sectional area; so large that air as it passes through it havingbeen forced thereinto by the blower A will always move at relatively low velocity. A A 'are a series of coal separating tables or decks fed from the plenum chamber 'A through conduits A discharging into vas chimneys A which in turn discharge and conduct air through the screen or deck A. V A A are hoods overlying each vdeck extending down thereabout but so disposed that there is a certain amount of clearance between the deck andthe hood. A is a dust manifold adapted to draw dust laden air from each of the hoods A and conduct it though the pipe A and discharge it into the suction side of the blower A driven by the motor A The blower A discharges through, a pipe B into a plenum chamber B The blower A and the plenum chamber B are of larger capacity than the blower A and the plenum chamber A because the blower and plenum chamber must handle and contain not merely the air that is handled and contained by and in the blower A and chamber A but that air plus twenty percent or more additional which has entered into the system through the hoods associated with each of the tables A B B are cleaning tables or decks preferably adaptedto handle'larger coal and requiring more air than the decks A. These decks are supplied with air under pressure from the plenum chamber or conduit B through the pipes B and vas chimneyB The fact that these tables requiremore'air thanthe tables A is provided for by the fact that we have now available in the plenum chamber or -conduit B moreair than we had in the plenum chamber or conduit Aibecause of the makeup which comes in between each hood and its table. B B area series of hoods associated with the tables, B communicating with the exhaust manifold B which in its turn discharges to the intake side of the fan B whence the air is drawn into the plenum chamber B ment. This deck 0 is enclosed by the'hood C' and the suction manifold G leads fromeach of the said hoods and communicates with the dust pipe C This dust pipe extends to and discharges into the suction side of the blower C and thence is discharged into the dust arrester A from which part of the dust laden air is drawn. The balance escaping out from the pipe C is dust free air.

The above discussion concerns itself only with the air originating in the cleaning system. The device, however, is intended to be used in connection with plants" where there are other sources ofdust laden air. have been illustrated more or less generally wherein D indicates an fArms classifying screen such as adapted to separate the coal into various sized classes 'such as are fed to the various tables. "Air is drawn from the hood D associated with the screen through the conduit D and discharged through the conductor G, since it is under suction-itdraws the dust laden air in from the Arms screen to discharge it to the dust arrester. D represents a hood, over a so-called Marcus conveyor and picking screen. Dust is drawn from this hood through-the conduit D and may be discharged thence from the conduit D to the conductor C whence it goesto the dust arrester or if it is necessary to have additional air for makeup in the second'battery of screens, the dust'laden air will be passed These decorate through the duct D to theintake side of the blower A. On the otherh'and, in connection with the plenum chamber B we might have an excess of air from the intermediate battery for what was needed 'for the coarse size battery of tables in which case air could lead out from the'plenum chamber B to the pipe D over the valve D to discharge again intothe conduit C. I

Obviously it might be possible to dispense with some of the fans here shown. Under some conditions a connection between the manifold B and the plenum chamber B might take the form of a simple conduit, though of course this would result in changing the plenum chamber from a pressure chamber as it is shown in Figure 1 to a suction chamber and this would of course make it impossible to bleed off air therefrom to the conduit D as is shown. The samesituation might prevail in connection with the blowers A and C in some conditions blower A couldbe dispensed with.

- The essential characteristic of this arrangement is that the tables are arranged in a series of groups, all the tables in a group receiving their air from a single air source and discharging their spent air from hoods above each table to a single discharge receiving member. The air so discharged may be then used to furnish air for a next series of tables or'may be passed through a dust arrester as the case may be but the general arrangement is such that we have interposed between groups oftables pressure manifolds and suction manifolds so arranged that the general path of air is from that part'of the system where the tables require a small amount of air through the system andthrough the table gradually increasing in air requirement back to adust collector from whichsome of the air returns to the system and the remainder is discharged from it.

In a somewhat similar but modified form shown in Figure 3 the dust collector E provides pure air which passes out through the pipe F1 to a blower E driven by a motor E Theblower provides air under pressure to the plenum chamber or manifold E. This manifold provides air through the pipes E to the tables E The spent air is caught in the hoods E and drawn up into the dust collecting manifold E which manifold is under an inactive pressure owing to the fact that the blowers E E are drawing air out of it. These blowers discharge air into the manifolds or plenum chambers E E from which the air is discharged from the pipes E E to the decks E E From the decks E the air is caught in the hoods E and sucked into the dust collecting manifold E The blower F draws the air out of the manifold E discharging into the pressure manifold F whence it is forced into the decks F hoods F and into the suction manifold F which communicates with the main suction pipe F, the blower F drawing dust laden air out of that pipe and discharging it into the dust arrester E. The dust collecting manifold F is fed from the hoods F associated with the tables E Air being drawn into that manifold by the blower 'F is discharged therefrom into the pipe F The auxiliary apparatuses in the house are taken care of by hoods Gr, associated in this case with two Arms screens, and the hood G in the Marcus house both of which discharge through pipes G G respectively into the suction pipe F and by the hood G discharging through a pipe G either into the suction pipe F or into the dust collecting manifold E as the case may be to provide additional make-up air at that point.

As illustrating the actual operation of devices such as this, we refer to Figure 1. lVe find that each of the tables A requires five thousand cubicfeet of air. Therefore the blower A must furnish twenty thousand cubic feet to the plenum chamber. There will be drawn out of each of the hoods A six thousand feet of air so that a total of twenty-four thousand cubic feet from the hoods A is forced by the blower A into the plenum chamber B It happens, however, that this is not enough for the next stage in the system and so we draw two thousand feet from the hood D over the Marcus chutes giving us a total of twenty-six thousand feet forced into the plenum chamber B The two decks B on the left require five thousandfeet each, the two decks B on the right require eight thousand feet each which makes our twenty-six thousand feet. From the two hoods B on the left is drawn siX thousand feet, that includes the live thousand feet forced into the deck and a thousand feet leakage in and around the hood. 'From the two hoods on the right is drawn ninety-six thousand feet each or a total of 31,200 feet forced by the blower B into the manifold B The two decks receiving air from the manifold 13", however, only need the one on the right 12,000 feet, the one on the left 10,000 or a total of 22,000 feet, therefore, the 9,200 feet passes out through the pipe D into the pipe C where it joins the 6,000 feet drawn from the Arms screen from the hood D, the 26,400 discharged from the hoods C made up 14,400 from the left hand hood and 12,000 from the right hand hood, all of which dust laden air plus 3,000 feet in addition drawn from the hood D through the pipe I) is forced by the fan G into the dust arrester. The total amount of air thus displaced being 44,600 feet. Since the air required for the manifold A is only 20,000 feet there is discharged from the dust arrester 24,600 feet.

'It will be noted in this arrangement that the biggest fan in the system, the one that takes all the dust laden air there is and feeds it to the dust ar'rester only displaces l l,600 feet. If the air was not reduced as indicated, this dust separator fan would have to handle 26,000 feet from the A tables in the first battery, 31,200 feet from the B tables in the second battery, 26,400 from the two C tables in the third battery, 6,000 feet from the Arms screen hood D and 5,000 feet from the auxiliary Marcus and other chutes and hoods D or a total of 94,600 feet of air. In other words by reducing this air we more than out in half the amount of air which must be circulated through the dust, arrester, thereby reducing the size of the dust arrester and the power required to operate it. 1 V

A similar analysis of the arrangement set out in Figure 3 is hardly worth making. Suffice it to say, that in this arrangement the fan F discharges into the dust arrester 61,000 cubic feet of air. Against this the fan would have to handle a maximum 112,600 feet if my arrangement were not used.

. bers containing as they do dust laden air furnish an especially effective separating zone next group.

. It will be noted that there is involved in each of these twosystems or in any systemmade according to this general plan, a series of mamfolds or plenum chambers where low air veloclty prevails. These plenum chamwhere thevelocity carried dust may be separated out. The veryfine floating dust is not separated but relatively large particles such as may have been drawn out by the air blast drop to the bottom and are carried out by the screw conveyors which are located in the bottoms of these manifolds as are indicated by letter H in Figure 3. 7

I I claim:

1. In a coal cleaning system a pluralityof separate groups of air cleaning tables, a single means for supplying air under pressure to the tables of the first group, a single means for withdrawing the spent dust laden. air fromthe first groupandfor supplying such air under pressure to the tables of the next group. I r M 2. In a coal cleaning system a plurality of separate groups of air cleaningtables, a single means for supplying air under pressure to the tables of the first group, a single means for withdrawing the spent dust laden air from the first group and for supplying such air under pressure tothe tables of the next group and a single means for Withdrawing all the spent dust laden air from'the-tables of the 3. In a coal cleaning system a plurality of separate groups of air cleaning tables, a single means for supplying airunder pressure tothe tables of the first group, a single means for withdrawing the spent dust laden air from the first group and for supplying such air under pressure to the tablesof the next group, a dust collector and a single means for withdrawing all the spent dust laden air. from the tables of the next group and discharging it into the dust collector.

4:. In a coal cleaning system a plurality of separate groups of air cleaning tables, a single, means for supplying air under pressure to the tables of the first group, a single means for withdrawing the spent dust laden air from the first group and for supplying such air under pressure to the tables of the nextgroup, a dust collector and a single means for withdrawing all the spent dust laden air from the tables of the next group and discharging it into the dust collector, and means for fur nishing cleaned air from the dust collector to the air supply means for the tables of the 5. In a coal cleaning system, a plurality of separate groups ofair cleaning tables, means for supplying air to them in series relation comprising, a'conduit communicating with the tables of the first group, means for forcing air under pressure into such conduit, a suction manifold communicating with the tables of the first group and means for withdrawing spent dust laden air from the tables through such manifold.

6. In a coal cleaning system, a plurality of separate groups of air cleaning tables, a conduit communicating with all the tables of the first group, means for forcing air under pressure into such conduit, a suction manifold I communicating withall the tables of the first group and means for withdrawing spent dust laden air from all the tables through such manifold, a conduit communicating with all the tables of the second group, means for discharging the air drawn through the manifold under pressure into the second conduit, a second suction manifold communicating with tables of the second group and means for drawing spent dust laden air therethrough from such tables.

r 7. In a coal cleaning system, a plurality of separate groups of air cleaning tables, aconduit communicating with all the tables of the first group, means for forcing air under pressure into such conduit, a suction manifold communicating with all the tables of the first group and means for withdrawing spent dust laden air from all the tables through such the first group, means for forcing air under pressure into such conduit, a suction manifold communicating with all the tables of the first group and means for withdrawing spent dust laden air from all the tables through such manifold, a conduit communicating with all the tables of the second group, means for discharging the air drawn through the manifold under pressure into the second conduit, a second suction manifold communicating with tables of the second group and means for drawing spent dust laden air therethrough from such tables, a dust arrester and means for discharging the dust laden air from the second manifold into the dust arr-ester, and means for supplying cleaned air from the dust arrester to the air forcing means which furnish air to the first named conduit.

9. In a coal cleaning system, a plurality of air cleaning tables having diderent air requirements and means for forcing air therethrough and withdrawing spent dust laden air therefrom, a dust arrester adapted to receive spent dust laden air from that part of the system where the air requirement is greatest and to supply cleaned air to that part of the system where the air requirement is least, the air forcing and withdrawing means being so arranged that dust laden air from tables of less requirement is supplied to tables of greater requirement so that only the amount of air discharged from the zone of greatest air requirement passes through the dust arrester, conduits leading from those parts of the system other than the tables where dust is generated adapted to draw dust laden air to and pass it through the dust arrester.

10. In a coal cleaning system, a plurality of groups of air cleaning tables, a dust arrester, separate pressure chambers and separate suction chambers associated with each group of tables, means for forcing air into the pressure chambers and for withdrawing dust laden air from the suction chambers, the dust laden air passing from a suction chamber to a pressure chamber whereby the air is re used passing through a plurality of tables in series.

11. In a coal cleaning system, a plurality of groups of air cleaning tables, a dust arrester, separate pressure chambers and separate suction chambers associated with each group of tables, means for forcing air into the pressure chambers and for withdrawing dust laden air from the suction chambers, the dust laden air passing from a suction chamber to a pressure chamber whereby the air is re-used passing through a plurality of tables in series, a dust arrester and conduits leading from the last suction chamber in the system to the dust arrester and from the dust arrester to the first pressure chamber in the system whereby some of the air is continuously circulated through the system.

12. In a coal cleaning system, a plurality of groups of air cleaning tables, means for supplying air toytheminiseries-1'6lation including a dust lairlfester, ;a 1 separate conduit adapted to supply {air 'under ;pressure to th e tables of each group, a separate dusticolleou ing suction manifold associated with :the tables of .each group, and :mechanical aneans for withdrawing dust settled :out of the air in each said .dust collecting mam-fold, {the arrangement being such that the presencenf the separate dust collecting mani fold in the series for lea-eh group prevents an overload of dust in the air supplied to any of (the groups.

'13. In acoal-cleaningqsystem, a ;plurality of groups of air cleaning tables, means for supplying :air .to them in series relation including adust arrester, :a separate conduit adaptedrtosupp'ly air underpressure to the tables of each group, a separateidustcollecting suction manifold associated with -the tables of each group, and mechanical ,means for withdrawingdust settled out of the air ineach said dust collecting manifold, imeam for supplying cleaned air from file/4111,51 rarrester tothe first conduit'of thesystem, the arrangement being suchthat the-presence of the separate dust collecting manifold in the series ;for each group prevents anzoverload of dust in the air supplied to any of the groups. p

14. In a coal .cleaningsystem, a plurality of groups of .air .cleaning ,tables, ,a' dust arrester, a separate conduit-adapted to supply air under. pressuretothe tables ofeach group, a separate dust collecting suction manifold associated with the tables, of each .group,.and mechanical means for withdrawing dust settled out of-the airin eaehsaid dustcollecting manifold, means for supplying cleaned air from the dust errester to .thefirstconduit of the system, means for supplying partially cleaned air :from the successive 'dust collecting manifolds to the next conduit in the series.

15. In a coal cleaning system, a plurality of groups of air cleaning tables, a dust arrester, a separate conduit adapted to supply air under pressure to the tables of each group, a separate dust collecting suction manifold associated with the tables of each group, and mechanical means for Withdrawing dust settled out of the air in each said dust collecting manifold, means for supplying cleaned air from the dust arrester to the first conduit of the system, means for supplying partially cleaned air from the successive dust collecting manifolds to the next conduit in the series, a main suction conduit, means for drawing air therethrough and discharging it into the dust arres-ter.

16. In a coal cleaning system, a plurality of groups of air cleaning tables, a dust arrester, a separate conduit adapted to supply air under pressure to the tables of each group, a separate dust collecting suction manifold associated with tl'ietaloles of each group and mechanical means for withdrawing dust settled out of the air in each said dust collecting manifold, means for supplying cleaned air from the dust arrester to the first conduit of the system, means for supplying 4 partially cleaned air from the successive dust collecting manifolds to the next conduit in the serles, a mam suction conduit, means for drawing air therethrough' and discharging it into the dust arrester, connections between v such conduit and some of the dust collecting series, a main suction conduit, means for manifolds whereby all the dust laden air leaving the system is discharged into the dust arrester. v a v y 1 7. In a coal cleaning system, a plurality of groups ofair cleaning tables, a dust arrester, a separate'con'duit adapted to supply air under pressureto thetables of each group, a separate dust collecting suction manifold associated withjthe tables of "each group and mechanical meansfor withdrawing dust settleclout of the air in each said dust collecting manifold, means} for supplying cleaned air from the dust arrester to the first conduit of the system, means for supplying'partially cleaned air from the successive dust collecting manifolds to the next conduit in" the drawing air therethrough and discharging it into the dust arrester, connections between such conduit and some of the dust collecting manifolds whereby all the dust laden air leaving the system is discharged into the dust arrester, hoods associated with all of the dust generating elements of the plant, conduits'leading from said hoods and dischargingintothe main dust collecting pipes.

Signed at Chicago, countyof Cook, and

State of Illinois, this 20th day of August,

I RAY w. ARMS. 

